Remote control system



y 1933- B. A. WITTKUHNS El AL 1,916,706

REMOTE CONTROL SYSTEM Filed Oct. 8, 1930 2 Sheets-Sheet 1 IN VE N TO R5BRUNO fl MTTKuH-s TTOR'NEY.

FREDERIC M.WAT ms July 4, 1933. B. A. WITTKUHNS ET AL 1,916,706

REMOTE CONTROL SYSTEM Filed Oct. 8, 1930 2 Sheets-Sheet 2 fkg am/c N.IA/Hi'lf/NS FATTRNEY.

Patented July 4, 1933 UNITED STATES PATENT? OFFICE BRUNO A. wIr'rKUKNs,or GHA'IHAK, NEW JERSEY, AND mans-mo m. WATKINS, or ronnsr HILLS, NEWYORK, ASSIGNORS 'ro SPERRY GYROSCOPE COMPANY, 'INC., or BROOKLYN, NEWYORK, a coaronA'rIoN or NEW YORK morn CONTROL sYsrEm Application filedOctober 8, 1930. Serial No. 487,358.

the like in accordance with the movements of the dlstant controller.Satisfactory means have been devised for the remote control ofindicators which require very little torque, among which ma be mentionedthe so-called Selsyn system. uch a system, however, 1s

not adapted for the turning of Ob ects requiring appreciable torque,smce the Selsyn motors were only accurate if not loaded. Such a systemcan only be used to turn heavy objects, therefore, by the employment ofan auxiliary power motor at the receiver. One

purpose of the present invention is to devise a remote control systemwhich is accurate and at the same time which has sufficient torque forthe rotation of objects having appreciable resistance and wlthout theemployment of an auxiliary power motor in addition to the repeatermotor. Accord ng to our invention we make use of variable 1mpedances,preferably resistances, one unit of which is connected to the sendinginstrument and another is driven by the receiving device. Alternatingcurrent, preferably three phase current, is used in connectiontherewith, one phase being fed through the resistances and thedifferential output amplified by a vacuum tube amplifier unit. The powermotor is preferably directly operated from the output of the amplifierunit by having rectly connected to one phase of the supply, the othertwo phases being connected to the output of the amplifier unit through asplit phase connection. Our three-phase motor at the receiver,therefore, is quite different from the ordinary A. C. repeater motor inthat it is supplied with ample current to exert full torques on thereceiver even though the displacement of the receiver from the properposition is very slight.

Referring to the drawings, 7

Fig. 1 is a wiring diagram showing one form of the invention theyassume, and

Fig. 2 discloses a wiring diagram of a modified form ofthe inventionshowing a different one of the three phase windings thereof dimethod ofleading in the supply current to the instruments.

' In the drawings the sending instrument represented by a dial 1 havinga crank 2. Connected so as to be driven from the dial is a variableresistance 3 which is shown as constructed in the form of a drum orcylinder on which is spirally wound the resistance Wire 4. A slidablecontact 5 is shown as engaging the Wire and it will be understood thatas the drum is revolved the contact 5 slides along the wire, thusincreasing the amount of resistance wire on one side of the cont-act anddecreasing it on the other side as the drum is revolved in onedirection. The opposite ends of resistance wire tare led through longconductors 6 and 7 to a similar drum 3 at the receiver.

In the form shown in Fig. 1, the polyphase supply is furnished by amotor generator set 8 and one wire thereof is connected to the slidingbrush 5 on drum 3 and another wire is connected to corresponding slidingbrush 5 on the drum 3. Preferably a variable resistance 10 is insertedbetween one side of the line and brush 5 and also a variable resistance11 and a resistance 12 are placed in a circuit between the two drums sothat the reresistances may be properly balanced to synchronize thesending and receiving instruments. Additional resistances 13 and 14 arealso shown for this purpose and to balance the resistance of the longtransmission wires (6 and 7).

The aforesaid resistances are balanced against each other somewhat inthe form of a Wheatstone bridge in which all four legs are variable andthe differential output is carried to an amplifier unit. As shown, theoutput is carried to an input transformer 15, the output of which is ledto the grid 16 of the first tube 17.

We prefer to use as an amplifier unit 18 the unit described and claimedin the copending application of Bruno A. Wittkuhns, one of the jointinventors hereto, Serial No. 433,- 562, filed March 6, 1930, anotherform of which is disclosed in the copending application of applicants,No. 381,660, filed July 27, 1929. According to our invention, all thecurrent for the resistors, motors and amplifying unit is furnished froma common polyphase supply, no other source of current being necessary.For supplying current of the proper voltage and phaserelatlon we haveshown a pair of transformers 25 and 26, the

, former being used to su ply plate potentials to the push-pull ampli er18 and the latter supplying the heating current for the tubes. As shown,the filament of the first tube is heat ed by secondary winding 26 of thetransformer 26. The output of the first tube passes through theinter-stage transformer 30 and thence to a pair of power tubes 18arranged in push-pull fashion. These tubes have their filaments lightedfrom the secondary 26" of transformer 26 and alternating current ofopposite potential is supplied to the plates thereof by connecting saidplates to the opposite ends of the secondary 25 of the transformer 25. I

We also employ a variable resistor 27 connected between the mid point 31of winding 25 and the mid point 32 of the winding 26 or in other wordsin series with the tubes 18. on account of the rectifying action of thepush-pull tubes 18 acting as a full wave rectifier, an analysis willshow that the current flowing through the resistor will be pulsatingdirect current which may be smoothed out by condensers 33 in a wellknown manner. We also connect to said resistor, preferably at anintermediate point 40, the mid point 35 of the winding 26. The resistor27 thus completes a circuit through the first tube as well as the othersand by connecting the grid of the first tube to an intermediate point 36on the resistor, the grid negative bias for this tube may be obtained. Afeed-back coupling is thus also obtained through the resistor. Also theproper D. C. positive plate potential is obtained from the same resistorby an intermediate tap 34 on the other side of point 40 from tap 36 andconnected through transformer 30 to the plate of the first tube. Thegrid bias for tubes 18 is obtained from said resistor by connecting thegrids thereof to point 37 on said resistor. The final output of thetubes is led through the output transformer 19. This transformer has twoprimaries 3839 connected respectively between the plates of the twotubes 18 and the secondary 25' of transformer 25. The secondary of saidtransformer has a center tap cross connected to a center tap on theprimary of transformer 25, thus forming a Scott connection by which twophases are supplied to the motor 20, the third phase being supplieddirectly from the third phase of the supply line. The result is that twophases of the motor 20 will be reversed whenever the indicator handle 2is reversed in direction, thus causing the motor 20 to drive thereceiver 22 and resistance 3 in the proper direction to restoresynchronism. The motor 20 is shown as geared to the receiver 22 which,as explained, may be any type of receiver, such as an indicator,searchlight, or gun, and to which is connected the resistance drum 3 onshaft 21.

For the purpose of synchronizing the sending and receiving instrumentswe have shown a synchronizing switch 23 which is preferably locatedadjacent the receiver. Switch 23 serves to break the connection from thesupply to the brush 5 on the sending instrument and to make a connectionfrom the supply to collector ring 9 on'the receiver, which is connectedto the mid point 10 of resistance 4. By throwing switch 23, therefore,from the operating position 0 to the synchronizing position S, thereceiver operator may ascertain at once whether his receiver issynchronized since he knows that when the switch is on S his receivershould read zero or some other known center reading. If it does not readproperly he adjusts resistance '11 until proper readings are obtained,when the switch is thrown back on 0. It may be noted that thissynchronizing operation maybe effected without interfering with ornotifying the sending operator or his instrument.

It should also be noted that very accurate following is obtained by ourinvention 'because of the double variation in resistances, that is, asone side of the two part resistance is increased the other isdiminished, thus giving double the accuracy of any resistancearrangement which contemplates the mere variation of one leg of aWheatstone bridge.

According to Fig. 2, instead of leadin in the supply to the resistancesthrough the s liding contacts 5 and 5', the supply may be led into theresistances through the two ends thereof, the resistances thus beingconnected in parallel across one phase of the supply. In such case thesliding brushes are connected to the input transformer 15 and the switch23 is placed in the wire'25 leading from the brush 5 to the transformer,the point S on the switch being connected as before to the collectorring 9. p

In accordance with the provisions of the patent statutes, we have hereindescribed the principle and operation of our invention, together withthe apparatus which we now consider to represent the best embodimentthereof, but we desire to have it understood that the apparatus shown isonly illustrative and that the invention can be carried out by othermeans; Also, while it is designed to use the various features andelements in the combination and relations described, some of these maybe altered and others omitted without interfering with the more generalresults outlined, and the invention extends to such use.

Having described. our invention, what we claim and desire to'secure byLetters Patent is:

1. In a remote control system, a sending device comprising a two-partresistance and variable means for increasing one part as the other isdecreased, a controlled device including an A. C. motor, a two-partresistance, and means driven by said motor for varying the same as saidfirst named resistance is varied, a thermionic amplifier unit in circuitbetween said resistances and motor, including a detector tube, a pair ofamplifier tubes arranged in push-pull fashion, and a resistanceconnected in series with the latter, and a common A. C. source connectedto said amplifier unit, said resistances and unit and also to said motorwhich supplies all the current necessary forthe operation of the system.

2. In a remote control system, a sending device comprising a two-partresistance and variable means for increasing one part as the other isdecreased, a controlled device including a three-phase motor, a two-partresistance, and means driven by said motor for varying the same as saidfirst-named resistance is varied, an amplifier unit in circuit betweensaid resistances and motor, and a three-phase source having a phaseconnected to said resistances and another phase connected to said motor.

3. In a remote control system, a sending device including a variableresistance, a receiver including a similar variable resistance, athree-phase motor for adjustin the latter resistance to correspond tothe ad ustment of the first-named resistance, a thermionicphase-shifting amplifier unit in circuit between said resistances andmotor, and a three-phase supply source having a phase connected to saidresistances and amplifier unit, and another phase connected to saidmotor.

4. In a remote control system, a sending device comprising a two-partresistance and variable means for increasing one part as the other isdecreased, a controlled device including an A. C. motor, a two-partresistance, and means driven by said motor for varying the same as saidfirst-named resistance is varied, an amplifier unit in circuit betweensaid resistances and motor, an A. C. source connected to saidresistances and unit and also to said motor, and means for synchronizingthe controlled device including a throw-over switch for temporarilyconnecting the said device to a predetermined fixed point on thefirst-mentioned resistance.

5. A remote control system as claimed in claim3 wherein said A. C.supply furnishes all potentials for the operation of the amplifier unit.

6. In a remote control system, a sending device including a variableresistance, a receiver including a similar variable resistance, athree-phase motor for adjustin the latter resistance to correspond tothe a justment of the first-named resistance, a thermionic amplifierunit in circuit between said resistances and motor, including a detectortube, a pair of amplifier tubes arranged in push-pull fashion, and aresistor connected in series with the latter, a. three-phase supplysource having a phase connected to said resistances and amplifier unitand another phase connected to said motor, said source supplying allcurrent necessary for the operation of the system and a synchronizingswitch adapted to connect the receiver to a predetermined point on thesending resistance.

In testimony whereof wehave aflixed our signatures.

BRUNO A. WITTKUHNS. FREDERIC M. WATKINS.

